Binary protocol¶
The binary protocol in Tarantool is a binary request/response protocol.
Notation in diagrams¶
0 X
+----+
| | - X + 1 bytes
+----+
TYPE - type of MsgPack value (if it is a MsgPack object)
+====+
| | - Variable size MsgPack object
+====+
TYPE - type of MsgPack value
+~~~~+
| | - Variable size MsgPack Array/Map
+~~~~+
TYPE - type of MsgPack value
MsgPack data types:
- MP_INT - Integer
- MP_MAP - Map
- MP_ARR - Array
- MP_STRING - String
- MP_FIXSTR - Fixed size string
- MP_OBJECT - Any MsgPack object
- MP_BIN - MsgPack binary format
Greeting packet¶
TARANTOOL'S GREETING:
0 63
+--------------------------------------+
| |
| Tarantool Greeting (server version) |
| 64 bytes |
+---------------------+----------------+
| | |
| BASE64 encoded SALT | NULL |
| 44 bytes | |
+---------------------+----------------+
64 107 127
The server instance begins the dialogue by sending a fixed-size (128-byte) text greeting
to the client. The greeting always contains two 64-byte lines of ASCII text, each
line ending with a newline character (\n). The first line contains the instance
version and protocol type. The second line contains up to 44 bytes of base64-encoded
random string, to use in the authentication packet, and ends with up to 23 spaces.
Unified packet structure¶
Once a greeting is read, the protocol becomes pure request/response and features a complete access to Tarantool functionality, including:
- request multiplexing, e.g. ability to asynchronously issue multiple requests via the same connection
- response format that supports zero-copy writes
The protocol uses msgpack for data structures and encoding.
The protocol uses maps that contain some integer constants as keys. These constants are defined in src/box/iproto_constants.h. We list common constants here:
-- user keys
<iproto_sync> ::= 0x01
<iproto_schema_id> ::= 0x05 /* also known as schema_version */
<iproto_space_id> ::= 0x10
<iproto_index_id> ::= 0x11
<iproto_limit> ::= 0x12
<iproto_offset> ::= 0x13
<iproto_iterator> ::= 0x14
<iproto_key> ::= 0x20
<iproto_tuple> ::= 0x21
<iproto_function_name> ::= 0x22
<iproto_username> ::= 0x23
<iproto_expr> ::= 0x27 /* also known as expression */
<iproto_ops> ::= 0x28
<iproto_data> ::= 0x30
<iproto_error> ::= 0x31
<iproto_sql_text> ::= 0x40
<iproto_sql_bind> ::= 0x41
<iproto_sql_info> ::= 0x42
-- -- Value for <code> key in request can be:
-- User command codes
<iproto_select> ::= 0x01
<iproto_insert> ::= 0x02
<iproto_replace> ::= 0x03
<iproto_update> ::= 0x04
<iproto_delete> ::= 0x05
<iproto_call_16> ::= 0x06 /* as used in version 1.6 */
<iproto_auth> ::= 0x07
<iproto_eval> ::= 0x08
<iproto_upsert> ::= 0x09
<iproto_call> ::= 0x0a
<iproto_execute> ::= 0x0b
<iproto_nop> ::= 0x0c
<iproto_type_stat_max> ::= 0x0d
-- Admin command codes
-- (including codes for replica-set initialization and master election)
<iproto_ping> ::= 0x40
<iproto_join> ::= 0x41 /* i.e. replication join */
<iproto_subscribe> ::= 0x42
<iproto_request_vote> ::= 0x43
-- -- Value for <code> key in response can be:
<iproto_ok> ::= 0x00
<iproto_type_error> ::= 0x8XXX /* where XXX is a value in errcode.h */
Both <header> and <body> are msgpack maps:
Request/Response:
0 5
+--------+ +============+ +===================================+
| BODY + | | | | |
| HEADER | | HEADER | | BODY |
| SIZE | | | | |
+--------+ +============+ +===================================+
MP_INT MP_MAP MP_MAP
UNIFIED HEADER:
+================+================+=====================+
| | | |
| 0x00: CODE | 0x01: SYNC | 0x05: SCHEMA_ID |
| MP_INT: MP_INT | MP_INT: MP_INT | MP_INT: MP_INT |
| | | |
+================+================+=====================+
MP_MAP
They only differ in the allowed set of keys and values. The key defines the type
of value that follows. If a body has no keys, the entire msgpack map for the body
may be missing. Such is the case, for example, for a <ping> request. schema_id
may be absent in the request’s header, meaning that there will be no version
checking, but it must be present in the response. If schema_id is sent in
the header, then it will be checked.
Authentication¶
When a client connects to the server instance, the instance responds with a 128-byte text greeting message. Part of the greeting is base-64 encoded session salt - a random string which can be used for authentication. The length of decoded salt (44 bytes) exceeds the amount necessary to sign the authentication message (first 20 bytes). An excess is reserved for future authentication schemas.
PREPARE SCRAMBLE:
LEN(ENCODED_SALT) = 44;
LEN(SCRAMBLE) = 20;
prepare 'chap-sha1' scramble:
salt = base64_decode(encoded_salt);
step_1 = sha1(password);
step_2 = sha1(step_1);
step_3 = sha1(salt, step_2);
scramble = xor(step_1, step_3);
return scramble;
AUTHORIZATION BODY: CODE = 0x07
+==================+====================================+
| | +-------------+-----------+ |
| (KEY) | (TUPLE)| len == 9 | len == 20 | |
| 0x23:USERNAME | 0x21:| "chap-sha1" | SCRAMBLE | |
| MP_INT:MP_STRING | MP_INT:| MP_STRING | MP_BIN | |
| | +-------------+-----------+ |
| | MP_ARRAY |
+==================+====================================+
MP_MAP
<key> holds the user name. <tuple> must be an array of 2 fields:
authentication mechanism (“chap-sha1” is the only supported mechanism right now)
and password, encrypted according to the specified mechanism. Authentication in
Tarantool is optional, if no authentication is performed, session user is ‘guest’.
The instance responds to authentication packet with a standard response with 0 tuples.
Requests¶
- SELECT: CODE - 0x01 Find tuples matching the search pattern
SELECT BODY:
+==================+==================+==================+
| | | |
| 0x10: SPACE_ID | 0x11: INDEX_ID | 0x12: LIMIT |
| MP_INT: MP_INT | MP_INT: MP_INT | MP_INT: MP_INT |
| | | |
+==================+==================+==================+
| | | |
| 0x13: OFFSET | 0x14: ITERATOR | 0x20: KEY |
| MP_INT: MP_INT | MP_INT: MP_INT | MP_INT: MP_ARRAY |
| | | |
+==================+==================+==================+
MP_MAP
- INSERT: CODE - 0x02 Inserts tuple into the space, if no tuple with same unique keys exists. Otherwise throw duplicate key error.
- REPLACE: CODE - 0x03 Insert a tuple into the space or replace an existing one.
INSERT/REPLACE BODY:
+==================+==================+
| | |
| 0x10: SPACE_ID | 0x21: TUPLE |
| MP_INT: MP_INT | MP_INT: MP_ARRAY |
| | |
+==================+==================+
MP_MAP
- UPDATE: CODE - 0x04 Update a tuple
UPDATE BODY:
+==================+=======================+
| | |
| 0x10: SPACE_ID | 0x11: INDEX_ID |
| MP_INT: MP_INT | MP_INT: MP_INT |
| | |
+==================+=======================+
| | +~~~~~~~~~~+ |
| | | | |
| | (TUPLE) | OP | |
| 0x20: KEY | 0x21: | | |
| MP_INT: MP_ARRAY | MP_INT: +~~~~~~~~~~+ |
| | MP_ARRAY |
+==================+=======================+
MP_MAP
OP:
Works only for integer fields:
* Addition OP = '+' . space[key][field_no] += argument
* Subtraction OP = '-' . space[key][field_no] -= argument
* Bitwise AND OP = '&' . space[key][field_no] &= argument
* Bitwise XOR OP = '^' . space[key][field_no] ^= argument
* Bitwise OR OP = '|' . space[key][field_no] |= argument
Works on any fields:
* Delete OP = '#'
delete <argument> fields starting
from <field_no> in the space[<key>]
0 2
+-----------+==========+==========+
| | | |
| OP | FIELD_NO | ARGUMENT |
| MP_FIXSTR | MP_INT | MP_INT |
| | | |
+-----------+==========+==========+
MP_ARRAY
Note that FIELD_NO is one based (starts from 1) unlike indices numbers which are usually zero based.
* Insert OP = '!'
insert <argument> before <field_no>
* Assign OP = '='
assign <argument> to field <field_no>.
will extend the tuple if <field_no> == <max_field_no> + 1
0 2
+-----------+==========+===========+
| | | |
| OP | FIELD_NO | ARGUMENT |
| MP_FIXSTR | MP_INT | MP_OBJECT |
| | | |
+-----------+==========+===========+
MP_ARRAY
Works on string fields:
* Splice OP = ':'
take the string from space[key][field_no] and
substitute <offset> bytes from <position> with <argument>
0 2
+-----------+==========+==========+========+==========+
| | | | | |
| ':' | FIELD_NO | POSITION | OFFSET | ARGUMENT |
| MP_FIXSTR | MP_INT | MP_INT | MP_INT | MP_STR |
| | | | | |
+-----------+==========+==========+========+==========+
MP_ARRAY
It is an error to specify an argument of a type that differs from the expected type.
- DELETE: CODE - 0x05 Delete a tuple
DELETE BODY:
+==================+==================+==================+
| | | |
| 0x10: SPACE_ID | 0x11: INDEX_ID | 0x20: KEY |
| MP_INT: MP_INT | MP_INT: MP_INT | MP_INT: MP_ARRAY |
| | | |
+==================+==================+==================+
MP_MAP
- CALL_16: CODE - 0x06 Call a stored function, returning an array of tuples. This is deprecated; CALL (0x0a) is recommended instead.
CALL_16 BODY:
+=======================+==================+
| | |
| 0x22: FUNCTION_NAME | 0x21: TUPLE |
| MP_INT: MP_STRING | MP_INT: MP_ARRAY |
| | |
+=======================+==================+
MP_MAP
- EVAL: CODE - 0x08 Evaulate Lua expression
EVAL BODY:
+=======================+==================+
| | |
| 0x27: EXPRESSION | 0x21: TUPLE |
| MP_INT: MP_STRING | MP_INT: MP_ARRAY |
| | |
+=======================+==================+
MP_MAP
- UPSERT: CODE - 0x09 Update tuple if it would be found elsewhere try to insert tuple. Always use primary index for key.
UPSERT BODY:
+==================+==================+==========================+
| | | +~~~~~~~~~~+ |
| | | | | |
| 0x10: SPACE_ID | 0x21: TUPLE | (OPS) | OP | |
| MP_INT: MP_INT | MP_INT: MP_ARRAY | 0x28: | | |
| | | MP_INT: +~~~~~~~~~~+ |
| | | MP_ARRAY |
+==================+==================+==========================+
MP_MAP
Operations structure same as for UPDATE operation.
0 2
+-----------+==========+==========+
| | | |
| OP | FIELD_NO | ARGUMENT |
| MP_FIXSTR | MP_INT | MP_INT |
| | | |
+-----------+==========+==========+
MP_ARRAY
Supported operations:
'+' - add a value to a numeric field. If the filed is not numeric, it's
changed to 0 first. If the field does not exist, the operation is
skipped. There is no error in case of overflow either, the value
simply wraps around in C style. The range of the integer is MsgPack:
from -2^63 to 2^64-1
'-' - same as the previous, but subtract a value
'=' - assign a field to a value. The field must exist, if it does not exist,
the operation is skipped.
'!' - insert a field. It's only possible to insert a field if this create no
nil "gaps" between fields. E.g. it's possible to add a field between
existing fields or as the last field of the tuple.
'#' - delete a field. If the field does not exist, the operation is skipped.
It's not possible to change with update operations a part of the primary
key (this is validated before performing upsert).
- CALL: CODE - 0x0a Similar to CALL_16, but – like EVAL, CALL returns a list of values, unconverted
CALL BODY:
+=======================+==================+
| | |
| 0x22: FUNCTION_NAME | 0x21: TUPLE |
| MP_INT: MP_STRING | MP_INT: MP_ARRAY |
| | |
+=======================+==================+
MP_MAP
Response packet structure¶
We will show whole packets here:
OK: LEN + HEADER + BODY
0 5 OPTIONAL
+------++================+================++===================+
| || | || |
| BODY || 0x00: 0x00 | 0x01: SYNC || 0x30: DATA |
|HEADER|| MP_INT: MP_INT | MP_INT: MP_INT || MP_INT: MP_OBJECT |
| SIZE || | || |
+------++================+================++===================+
MP_INT MP_MAP MP_MAP
Set of tuples in the response <data> expects a msgpack array of tuples as value
EVAL command returns arbitrary MP_ARRAY with arbitrary MsgPack values.
ERROR: LEN + HEADER + BODY
0 5
+------++================+================++===================+
| || | || |
| BODY || 0x00: 0x8XXX | 0x01: SYNC || 0x31: ERROR |
|HEADER|| MP_INT: MP_INT | MP_INT: MP_INT || MP_INT: MP_STRING |
| SIZE || | || |
+------++================+================++===================+
MP_INT MP_MAP MP_MAP
Where 0xXXX is ERRCODE.
An error message is present in the response only if there is an error; <error>
expects as value a msgpack string.
Convenience macros which define hexadecimal constants for return codes can be found in src/box/errcode.h
Replication packet structure¶
-- replication keys
<server_id> ::= 0x02
<lsn> ::= 0x03
<timestamp> ::= 0x04
<server_uuid> ::= 0x24
<cluster_uuid> ::= 0x25
<vclock> ::= 0x26
-- replication codes
<join> ::= 0x41
<subscribe> ::= 0x42
JOIN:
In the beginning you must send initial JOIN
HEADER BODY
+================+================++===================+
| | || SERVER_UUID |
| 0x00: 0x41 | 0x01: SYNC || 0x24: UUID |
| MP_INT: MP_INT | MP_INT: MP_INT || MP_INT: MP_STRING |
| | || |
+================+================++===================+
MP_MAP MP_MAP
Then instance, which we connect to, will send last SNAP file by, simply,
creating a number of INSERTs (with additional LSN and ServerID)
(don't reply). Then it'll send a vclock's MP_MAP and close a socket.
+================+================++============================+
| | || +~~~~~~~~~~~~~~~~~+ |
| | || | | |
| 0x00: 0x00 | 0x01: SYNC || 0x26:| SRV_ID: SRV_LSN | |
| MP_INT: MP_INT | MP_INT: MP_INT || MP_INT:| MP_INT: MP_INT | |
| | || +~~~~~~~~~~~~~~~~~+ |
| | || MP_MAP |
+================+================++============================+
MP_MAP MP_MAP
SUBSCRIBE:
Then you must send SUBSCRIBE:
HEADER
+===================+===================+
| | |
| 0x00: 0x42 | 0x01: SYNC |
| MP_INT: MP_INT | MP_INT: MP_INT |
| | |
+===================+===================+
| SERVER_UUID | CLUSTER_UUID |
| 0x24: UUID | 0x25: UUID |
| MP_INT: MP_STRING | MP_INT: MP_STRING |
| | |
+===================+===================+
MP_MAP
BODY
+================+
| |
| 0x26: VCLOCK |
| MP_INT: MP_INT |
| |
+================+
MP_MAP
Then you must process every query that'll came through other masters.
Every request between masters will have Additional LSN and SERVER_ID.
XLOG / SNAP¶
XLOG and SNAP files have nearly the same format. The header looks like:
<type>\n SNAP\n or XLOG\n
<version>\n currently 0.13\n
Server: <server_uuid>\n where UUID is a 36-byte string
VClock: <vclock_map>\n e.g. {1: 0}\n
\n
After the file header come the data tuples.
Tuples begin with a row marker 0xd5ba0bab and
the last tuple may be followed by an EOF marker
0xd510aded.
Thus, between the file header and the EOF marker, there
may be data tuples that have this form:
0 3 4 17
+-------------+========+============+===========+=========+
| | | | | |
| 0xd5ba0bab | LENGTH | CRC32 PREV | CRC32 CUR | PADDING |
| | | | | |
+-------------+========+============+===========+=========+
MP_FIXEXT2 MP_INT MP_INT MP_INT ---
+============+ +===================================+
| | | |
| HEADER | | BODY |
| | | |
+============+ +===================================+
MP_MAP MP_MAP
See the example in the following section.